I have sold a lot of these engines, not one has given me or the club members any trouble. Sure some of them have to be fined tuned other then the factory setting. All you have to know is how. what I still don't understand is why no one that has trouble said anything about sending them back to Horizon to get fixed. They give you three years. I sell the trainer in the store and taught at the field, not one dead stick.. I have sold them since day one and not one customer has asked to replace it. I still say if the engine can't be tuned it's not the engines fault. Now that's just my experience with them. Dennis